For me the easiest tell is the up front, unprompted, and unsolicited declaration of nonpoliticalness. When someone takes the time and expends the breath to announce how nonpolitical they are, what follows is almost always a rant about how everything/everyone else is too political these days, and that of course leads into something between status quo advocacy and outright reactionary/regressive sentiments for some fabled time before those wicked politics were visible to the nonpolitical ranter. 
People that are hostile to service workers. Some just want to take some ideological stand against tipping when the service worker doesn't really have a choice and needs those tips to survive in the current unjust system in a way where ideological purity gestures toward that service worker just look like being a greedy and sanctimonious asshole. The worst of such people will actually declare, shamelessly, that they believe that service workers don't deserve a living wage. The implications of that are 
worthy.
I may get shit for this, but I'll say it anyway: this hair and beard combo, seen on living people. 
I have yet to meet anyone in person with that look that wasn't a chud.
(If one of you is a comrade with that look, I am sorry in advance for the prejudice and if I ever meet you in person I will atone by buying you a drink or something.)
Lest I look like a chud, I'll make sure that whenever I ask "So, you watch anime?" that I immediately follow it up with "Did you know that in that Little Witch Academia episode where the non-humans at the magical academy unionize and strike, that when Akko joins the non-humans (respect), that the kanji on her headband are based on a style of typography called gebaji? The word gebaji derives from gebaruto, from German Gewalt. In Japanese, gebaruto generally refers to violence perpetrated by leftist student activists in the '50s and '60s. Their protest signs used a distinctive style of bold, angular, 'common man' typography, and this typographic style is to this day associated with or used as shorthand for leftist particularly student activism. Gebaji is also known by other names, such as Zengakurenmoji — you might recognize the name 'Zengakuren' from their role in the famous riot at Sanrizuka in 1985. Anyways, here's a photo of a younger Hayao Miyazaki at some kind of labor action of the union for Studio Toei. You can see that he's wearing a headband just like the one Akko wore. You gotta love a union man, eh? By the way, have you seen the, like, anime music video created by the Japanese Communist Party? Heck, do you watch any donghua, for that matter?"
COMRADE AKKO UNDERSTANDS THAT WE CAN'T JUST "METAMORPHIE FOCIESSE" OUR WAY TO A CLASSLESS, MONEYLESS SOCIETY... DO YOU?
that music video blew my goddamn mind hahahahahaha.
Complete tangent, but I'm trying to get into wuxia and xianxia right now and anyone I ask about it just tells me "Have you read Romance of the Three Kingdoms?"
Bitch, if I said I was looking for a good romance novel and you recommended Pride and Prejudice i might just slap you. Give me an anime or something. Smh
why does this thread have so many interesting eclectic comments lol, of all the threads to bring this stuff out of the woodwork it was "what are some tells that someone is fash"
anyway that was cool, thanks for sharing